1. Field of the Invention
The present invention relates to a switching circuit used in a switching network like an ATM (Asynchronous Transfer Module) switching system, and more particularly to a switching circuit having a monitor function for detecting switching errors or other problems in the switching circuit.
2. Description of the Related Art
ATMs are expected to be widely utilized in future telecommunication networks. One network architecture using an ATM is described by M. A. Henrion, K. J. Schrodi et al. entitled "Switching Network Architecture For ATM Broadband Communications" XIII International Switching Symposium, Session A47, 1990. The ATM switching network described in the above document uses a plurality of switching matrices for transferring information. Usually, each switching matrix has a plurality of switch paths between input lines and output lines, and the switch paths are selected or transferred by a switching control circuit.
On the other hand, a monitor circuit monitors output data of the ATM switching network by detecting output data of the network. However, the monitor circuit does not monitor the operation of the respective switch path in the switching matrix. Therefore, it is difficult to quickly determine problems in the switching matrix, when the problems are located in an unused switch path. If an unused or unworked switch path is selected for connecting a particular input and output line for a change without knowledge of problems therein, a major disturbance can occur on the ATM switching network.